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United States Patent |
5,104,291
|
Morrison
|
*
April 14, 1992
|
Variable pitch propeller blade hub and drive and adjusting mechanism
therefor
Abstract
A hollow hub has around its exterior a plurality of apertures for
individually receiving a respective cylindrical inner end portion of one
of a plurality of axially rotatable propeller blades. Additionally, the
hub has around its exterior a plurality of arcuate recesses for (a)
individually receiving an inner portion of one of the respective propeller
blades when the cylindrical inner end portion of that blade is received in
one of the apertures, and (b) accommodating arcuate movement of the blade
inner portion upon axial rotation of the cylindrical inner end portion of
the blade.
Inventors:
|
Morrison; Douglas M. (Box 733-A, Highway 304, Thibodaux, LA 70301)
|
[*] Notice: |
The portion of the term of this patent subsequent to May 21, 2008
has been disclaimed. |
Appl. No.:
|
600673 |
Filed:
|
October 22, 1990 |
Current U.S. Class: |
416/168R; 416/220R |
Intern'l Class: |
B63H 001/00; B63H 003/00 |
Field of Search: |
416/153,163,164,167,168 R,166,147,220 R
|
References Cited
U.S. Patent Documents
494014 | Mar., 1893 | McGlasson | 416/168.
|
573977 | Dec., 1896 | Hubbard | 416/166.
|
655958 | Aug., 1900 | Carlsson | 416/237.
|
810032 | Jan., 1906 | Brown | 416/167.
|
833364 | Oct., 1906 | Arthur | 416/237.
|
1332475 | Mar., 1920 | Spitler | 416/163.
|
1407080 | Feb., 1922 | Overturf | 416/167.
|
1491589 | Apr., 1924 | Dzus | 416/39.
|
1546554 | Jul., 1925 | Ross | 416/237.
|
1713446 | May., 1929 | Peterson | 416/247.
|
1779050 | Oct., 1930 | Schroder | 416/168.
|
1806325 | May., 1931 | Wooden | 416/205.
|
1896280 | Jul., 1932 | Roemisch | 156/418.
|
2084655 | Dec., 1935 | Roberts | 416/166.
|
2282436 | May., 1942 | Taylor | 416/234.
|
2354465 | Jul., 1944 | Le Bert | 416/147.
|
2391011 | Feb., 1946 | Raulerson | 416/168.
|
2470517 | May., 1949 | Obrist | 416/220.
|
2478244 | Aug., 1949 | Cooley | 416/163.
|
2554716 | May., 1951 | Melius | 416/239.
|
2684654 | Jul., 1954 | Johnson | 416/237.
|
2711796 | Jun., 1955 | Amiot | 416/152.
|
2870848 | Jan., 1959 | Liaaen | 416/157.
|
2885013 | May., 1959 | Steiner | 416/163.
|
2939334 | Jun., 1960 | Beckjord | 416/167.
|
2953208 | Sep., 1960 | O'Connor | 416/147.
|
3027864 | Apr., 1962 | Polson | 416/247.
|
3122207 | Feb., 1964 | Mades | 416/151.
|
3138136 | Jun., 1964 | Nichols | 167/.
|
3282351 | Nov., 1966 | Troutman | 416/167.
|
3518022 | Jun., 1970 | Adams | 416/27.
|
3794441 | Feb., 1974 | Johnson | 416/167.
|
3795463 | Mar., 1974 | Herbert | 416/207.
|
4842483 | Jun., 1989 | Geary | 416/93.
|
5017090 | May., 1991 | Morrison | 416/212.
|
Foreign Patent Documents |
463179 | Feb., 1950 | CA | 416/163.
|
727968 | Nov., 1942 | DE | 416/136.
|
467096 | Dec., 1914 | FR | 416/168.
|
538548 | Jun., 1922 | FR | 416/166.
|
686214 | Jul., 1930 | FR | 416/163.
|
1177427 | Jun., 1957 | FR | 416/168.
|
453536 | Dec., 1949 | IT | 416/167.
|
547875 | Sep., 1956 | IT | 416/164.
|
57-46091 | Mar., 1982 | JP | 416/167.
|
28468 | Mar., 1917 | NO | 416/166.
|
343777 | Feb., 1931 | GB | 416/167.
|
614731 | Dec., 1948 | GB | 416/164.
|
Primary Examiner: Look; Edward K.
Assistant Examiner: Nguyen; Hoang
Attorney, Agent or Firm: Sieberth; John F.
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
This is a division of my prior copending application Ser. No. 308,329,
filed Feb. 7, 1989, which in turn is a continuation-in-part of my prior
application Ser. Number 174,428, filed Mar. 28, 1988, all disclosure of
which is incorporated herein by reference.
Claims
What is claimed is:
1. A hollow hub having an exterior wall and at spaced-apart locations
around the exterior perimeter of the wall and extending therethrough, a
plurality of apertures for individually receiving a respective cylindrical
inner end portion of one of a plurality of axially rotatable propeller
blades having a leading edge portion which has (i) an inner leading edge
segment and (ii) an inner end portion, said hub additionally having
disposed at spaced-apart locations around the exterior perimeter of said
wall by not extending therethrough, a plurality of arcuate recesses
shaped, sized and positioned for (a) individually receiving therein said
inner end portion of said leading edge portion of one of the respective
propeller blades when the cylindrical inner end portion of that blade is
received in one of said apertures, and (b) accommodating arcuate movement
of said inner end portion of said leading edge portion upon axial rotation
of said blade, to enable said inner leading edge segment to project
substantially tangentially from said hub when the blade is transverse or
substantially transverse to the axis of said hub; the exterior perimeter
of the hub and the forward edge portion of each said recess becoming
deeper when proceeding in the direction from (A) the place where said
blade is transverse to the axis of the hub to (B) either one of the
respective ends of the recess, and having a maximum depth less than the
thickness of said wall such that the recess does not cut through said
wall.
2. An article as claimed in claim 1 wherein said hub includes means
translating linear motion into opposed rotational movement of said
cylindrical inner end portions so that the pitch of the blades can be
adjusted by such rotational movement of said cylindrical inner end
portions.
3. An article as claimed in claim 1 further characterized in that said
arcuate recesses each have two opposite end wall portions positioned and
adapted to serve as stops to prevent, by virtue of abutment between an
inner portion of the respective blades and one of said end wall portions,
over-rotation of the blades in either direction when the blades are
rotated on the axis of their respective cylindrical inner end portions.
4. A cylindrical hollow hub having a cylindrical exterior wall, said wall
having on opposite sides thereof and extending therethrough, an aperture
for receiving a cylindrical stub disposed on the inner end portion of an
axially rotatable propeller blade having a leading edge portion which has
(i) an inner leading edges segment and (ii) an inner end portion, said hub
additionally having disposed on opposite sides of the exterior perimeter
of said wall and in proximity to the respective apertures, an arcuate
recess shaped; sized and positioned for (a) individually receiving therein
said inner end portion of said leading edge portion of one of the
respective propeller blades when the cylindrical stub on the inner end
portion of that blade is received by the proximate aperture, and (b)
accommodating arcuate movement of said inner end portion of said leading
edge portion upon axial rotation of said stub and blade, to enable said
inner leading edge segment to project substantially tangentially from said
hub when the blade is transverse or substantially transverse to the axis
of said hub; each said recess becoming deeper when proceeding in the
direction from (A) the place where said blade is transverse to the axis of
the hub to (B) either one of the respective ends of the recess, and having
a maximum depth less than the thickness of said wall such that the recess
does not cut through said wall.
5. An article as claimed in claim 4 wherein said hub includes means
translating linear motion into opposed rotational movement of said stubs
so that the pitch of the blades can be adjusted by such rotational
movement of said stubs.
6. An article as claimed in claim 4 further characterized in that said
arcuate recesses each have two opposite end wall portions positioned and
adapted to serve as stops to prevent, by virtue of abutment between the
inner end portion of the respective blades and one of said end wall
portions, over-rotation of the blades in either direction when the blades
are rotated on the axis of their respective stubs.
7. Apparatus according to claim 5 further characterized in that said means
comprises (i) a yoke mounted on the end of a pitch adjusting shaft, the
yoke including a pair of ears extending longitudinally beyond the end of
the pitch adjusting shaft; (ii) a pair of lobes, each integral with a
respective stub and extending radially along an axis perpendicular to the
axis of the stub thereby forming a crank thereon, said lobes extending in
generally opposite directions from each other; and (iii) a pair of links,
each pivotally connected to a respective ear of the yoke and to the crank
of the proximate stub.
8. A variable pitch propeller drive and adjusting mechanism which
comprises:
a) a hollow drive shaft;
b) an open-ended hollow housing mounted on the end of the shaft and
rotatable therewith;
c) a hub end cap detachably secured to the housing to cover the open end
thereof and thereby form a hollow hub;
d) a pitch adjusting shaft rotatable with and longitudinally moveable in
the drive shaft;
e) means within the hub translating longitudinal movement of the pitch
adjusting shaft into opposed rotational movement of the
hereinafter-referred-to cylindrical stubs about an axis perpendicular to
an extending through the axis of the drive shaft;
said hollow hub being characterized by having a cylindrical exterior wall,
said wall having on opposite sides thereof and extending therethrough, an
aperture for receiving a cylindrical stub disposed on the inner end
portion of an axially rotatable propeller blade having a leading edge
portion which has (i) an inner leading edge segment and (ii) and inner end
portion, said hub additionally having disposed on opposite sides of the
exterior perimeter of said wall and in proximity to the respective
apertures, an arcuate recess shaped, sized and positioned for (1)
individually receiving therein said inner end portion of said leading edge
portion of one of the respective propeller blades when the cylindrical
stub on the inner end portion of that blade is received by the proximate
aperture, and (2) accommodating arcuate movement of said inner end portion
of said leading edge portion upon axial rotation of said stub and blade,
to enable said inner leading edge segment to project substantially
tangentially from said hub when the blade is transverse or substantially
transverse to the axis of said hub; each said recess becoming deeper when
proceeding in the direction from (A) the place where said blade is
transverse to the axis of the hub to (B) either one of the respective ends
of the recess, and having a maximum depth less than the thickness of said
wall such that the recess does not cut through said wall.
9. Apparatus according to claim 8 further characterized in that said means
within the hub comprises (i) a yoke mounted on the end of the pitch
adjusting shaft, the yoke including a pair of ears extending
longitudinally beyond the end of the pitch adjusting shaft; (ii) a pair of
lobes, each integral with a respective stub and extending radially along
an axis perpendicular to the axis of the stub thereby forming a crank
thereon, said lobes extending in generally opposite directions from each
other; and (iii) a pair of links, each pivotally connected to a respective
ear of the yoke and to the crank of the proximate stub.
10. An article as claimed n claim 4 wherein said hub includes means
translating linear motion into opposed rotational movement of said stubs
so that the pitch of the blades can be adjusted by such rotational
movement of said stubs; and wherein said arcuate recesses each have two
opposite end wall portions positioned and adapted to serve as stops to
prevent, by virtue of abutment between the inner end portion of the
respective blades and one of said end wall portions, over-rotation of the
blades in either direction when the blades are rotated on the axis of
their respective stubs.
11. An article as claimed in claim 10 wherein said means comprises (i) a
yoke mounted on the end of a pitch adjusting shaft, the yoke including a
pair of ears extending longitudially beyond the end of the pitch adjusting
shaft; (ii) a pair of lobes, each integral with a respective stub and
extending radially along an axis perpendicular to the axis of the stub
thereby forming a crank thereon, said lobes extending in generally
opposite directions from each other; and (iii) a pair of links, each
pivotally connected to a respective ear of the yoke and to the crank of
the proximate stub.
12. An article as claimed in claim 8 wherein said arcuate recesses each
have two opposite end wall portions positioned and adapted to serve as
stops to prevent, by virtue of abutment between the inner end portion of
the respective blades and one of said end wall portions, over-rotation of
the blades in either direction when the blades are rotated on the axis of
their respective stubs.
13. An article as claimed in claim 9 wherein said arcuate recesses each
have two opposite end wall portions positioned and adapted to serve as
stops to prevent, by virtue of abutment between the inner end portion of
the respective blades and one of said end wall portions, over-rotation of
the blades in either direction when the blades are rotated on the axis of
their respective stubs.
Description
TECHNICAL FIELD
This invention relates to means for controlled propulsion of boats, and in
this context to new, useful and highly efficacious variable pitch
propeller blade constructions, and drive and adjusting mechanisms for such
propellers.
BACKGROUND
Various mechanisms for adjusting the pitch of rotatable blades (propellers,
fan blades, etc.) have been described heretofore. See for example U.S.
Pat. Nos. 494,014; 573,977; 810,032; 1,332,475; 1,407,080; 1,491,589;
1,779,050; 1,806,325; 1,869,280; 2,084,655; 2,354,465; 2,394,011;
2,470,517; 2,478,244; 2,711,796; 2,870,848; 2,885,013; 2,939,334;
3,122,207; 3,138,136; 3,518,022; 3,795,463; Canadian 463,179; French
1,177,427; Italy 547,875; and Japan 57-46091.
Although differently shaped blades have been described for use in driving a
boat or other vessel through water, the most commonly used type involves a
blade having a helically shaped (twisted) configuration.
Heretofore, when flat bottom boats or other boats of shallow draft entered
marshy areas choked with vegetation or thick muddy areas covered with but
a few inches of water--situations which can readily be encountered in
swamps such as exit in southern Louisiana and in other swampy regions--it
was very likely that the boats would become mired and bogged down so that
they could not move in any direction. Contributing to the problem was the
fact that the driving mechanisms for small boats available on the open
market rotate in only one direction and are equipped with helically
twisted propellers that can readily become entangled in thick vegetation.
SUMMARY OF THE INVENTION
An object of this invention is to provide new, useful and highly
efficacious variable pitch propeller blade constructions which work well
in propelling boats, especially flat bottom boats, through very shallow
water, or mud, or swampy or marshy areas, even those choked with
vegetation.
A further object is to provide a variable pitch propeller blade
configuration which when used with conventionally sized and rated outboard
motors or engines (e.g., 10-25 hp) provides the power needed to drive flat
bottom boats and other boats of shallow draft through wet muds and
marshes, even when the area is choked with swamp grasses and other similar
vegetation commonly encountered in swampy and marshy areas.
Still another object is to provide a variable pitch propeller blade
configuration which can be used to propel the boat--including flat bottom
boats--through wet muds and marshes under conditions of the type just
described, yet which can propel the very same boat at a relatively high
rate of speed through open water, again without need for more powerful
motors or engines than are customarily used as outboard motors for boats.
Yet another object is to provide variable pitch propeller blades that can
be adjusted by the operator through a continuum of positions ranging from
fast forward to fast reverse so that the boat can be operated at a full
range and variety of speeds, can be stopped rapidly, and can be maneuvered
with precision.
A further object is to provide a propeller blade configuration and
mechanism enabling the operator to run the boat at any particular speed
within a continuous range of speeds, and, without changing engine speed,
swiftly stop the boat and even reverse its direction of movement if the
need or desire to do so arises.
Another object is to provide a mechanism that will enable the operator to
run the boat at very slow or fast speeds with a minimum of noise.
Still another object is to provide a propeller blades and propeller blade
assemblies that can be serviced and repaired easily and quickly.
These and other objects, features and embodiments of this invention will
become further apparent as the discussion proceeds.
In accordance with one embodiment of this invention a variable pitch
propeller blade is provided in which the blade is of generally planar
configuration, i.e., there is no twist or helical configuration in the
blade. One portion of the blade (the leading edge portion) is relatively
thin and another portion (a median and/or a trailing edge portion) is
somewhat thicker to provide the necessary strength and rigidity to the
blade. The blade is configured such that the thin leading edge portion of
the blade has a swept back or retracted curvature along a substantial
portion of its length when proceeding in the direction of inner end to
outer end. While such blades may have generally convex or concave outer
surfaces (faces), it is preferable that they have substantially flat outer
surfaces. In other words, the front and rear faces of such blades may be
convex or slightly concave between the leading and trailing edge portions,
but preferably, are substantially flat between the leading and trailing
edge portions. Affixed to the inner ends of each such blade is a means
(preferably a cylindrical stub or the like) for rotating the blade in a
continuous series of planes whereby the position of the blade can be
adjusted to and from a fast forward position through neutral and to and
from a fast reverse position, and can be set at any and all stages
therebetween so that the boat may be operated in either direction (forward
or reverse) without adjusting the speed of the engine and can be
manuevered with quick response and precision. Indeed, these blades enable
the boat to be rocked back and forth while the boat is being turned in a
very small space, and this in turn enables the boat to be disengaged from
thick vegetation rather than becoming mired and bogged down as is the case
with boats equipped with conventional propellers and propulsion systems.
When the blade is in a forward propelling position the leading or sharp
edge of the blade projects forwardly of the plane which is perpendicular
(transverse) to the axis of the propeller shaft. When the blade is in a
rearward propelling position the leading or sharp edge of the blade
projects rearwardly of the plane perpendicular (transverse) to the axis of
the propeller shaft). And when the blade is in its neutral position
(propelling neither forwardly or rearwardly) the plane of the blade falls
substantially along the plane which is perpendicular (transverse) to the
axis of the propeller shaft. The angular displacement between the plane of
the blade and the perpendicular plane governs the speed at which the boat
will be propelled: the greater the angle, the higher the speed. For most
types of general service, provision will be made to allow the angular
displacement between the plane of the blade and the perpendicular plane to
be adjusted to as much as 45.degree. in both forward and reverse. However
the limits of adjustment for these ranges may be varied as deemed
necessary or desirable. Normally, and preferably, these stubs in turn will
be received within a hub containing a suitable mechanism for applying a
rotational torque to the stubs to rotate the stubs about their respective
axes and thereby rotate the planar blades and adjust their pitch while at
the same time causing the blades to be rotated about the axis of the
propeller shaft so that the leading edge is always the forwardmost portion
of the blade cutting into the water (whether operating in forward, reverse
or neutral). In a preferred embodiment two such blades are disposed on and
extend from opposite sides of a rotatable hub and are operatively
connected to means for translating linear motion into axial rotational
torque upon the blade stubs for adjusting the pitch of the blades as
desired by the operator.
Flat planar blades of the type described in the immediately preceding
paragraph generate the greatest amount of power both in the forward and
rearward directions. Thus such essentially flat planar blades with a
relatively sharp leading edge portion and a relatively thicker median and
/or trailing edge portion are preferred for use in mud boats and other
similar flat bottom boats to be used in swamps and marshes, especially
where the water is as shallow as one to two inches or less, and where
thick mud and/or heavy vegetation may be encountered. For convenience
these blades will often be referred to hereinafter as the "flat planar
blades".
In another embodiment of this invention a variable pitch propeller blade of
the type described above is provided differing in that the plane of the
blade is curved or bent along its length. The curvature commences at a
locus at least about one-half (preferably between about one-half and about
three-fourths, most preferably about two-thirds) the distance from the
innermost portion of the blade to the outermost portion of the blade. The
direction of the bend is always toward the front of the boat. Thus there
are basically two such curved blade configurations, depending upon the
direction in which the hub and blades are to be rotated. If the propeller
drive train is arranged so that the hub and blades rotate clockwise (when
viewed from behind the propeller and looking in the direction of forward
boat travel) the plane of the blade curves toward the front of the boat
and when the blades are in the 12 o'clock position, the relatively sharp
leading edge is toward the right hand side. However, if the propeller
drive train is arranged so that the hub and blades rotate
counter-clockwise (when viewed from behind the propeller and looking in
the direction of forward boat travel) the plane of the blade again curves
toward the front of the boat, but when the blades are in the 12 o'clock
position, the relatively sharp leading edge is toward the left hand side.
It is to be noted that although the outer end portion of the blade is bent
in the appropriate direction (i.e., toward the front of the boat), the
blade is not helically twisted. Rather, the blade when viewed edgewise is
substantially flat, but bent along an outer portion of its length. For
convenience these blades will often be referred to hereinafter as the
"/bent planar blades", and collectively the "flat planar blades" and the
"bent planar blades" will often be referred to collectively hereinafter as
the "planar blades". It will thus be understood that in all cases the
planar blades have a relatively sharp, outwardly receding or retracted
(swept back) leading edge and a somewhat thicker median zone or trailing
edge (which may itself be rounded off, squared off or even tapered down in
thickness for a short distance), and most preferably their front and rear
faces are substantially flat (as distinguished from being radially
twisted).
The bent planar blades generally do not generate quite as much power in the
forward and rearward directions as the flat planar blades, yet they still
can provide enough power to move even flat bottom boats through reasonably
thick muds and marshes. An advantage of the bent planar blades is that
they make possible the attainment of higher boat speeds than the flat
planar blades. Accordingly the bent planar blades represent an excellent
compromise between speed and power, and are thus well suited for use in
mud boats and other similar flat bottom boats to be used both in open
water and in swamps and marshes, even where water as shallow as one to two
inches and where mud and/or vegetation may be encountered.
The receding or swept back (retracted) curved leading edge is one of the
very important features enabling the blades, especially the flat planar
blades, to cut through thick muds covered with but a few inches of water
or through marshy areas choked with vegetation such as swamp grasses,
water lilies, and the like. This and the fact that the planar blades of
this invention are adapted to be rotated on the axis of their stubs
enables the blades to maneuver the boats back and forth with great
precision in extricating the boat from thickly vegetated areas, to cut
through snags and snares that would tend to foul conventional propellers,
and to shed vegetation that would choke and foul conventional propellers.
Helically twisted and even planar blades that are paddle shaped with more
or less convex leading and trailing edges are incapable of performing
effectively under such conditions. Likewise planar blades with more or
less straight leading edges cannot operate effectively under these
conditions.
It will be appreciated that the receding or swept back (retracted) curved
leading edge need not be (but preferably is) composed of a smooth
uninterrupted curve. In lieu thereof the curvature of the swept back
leading edge may include in whole or in part a series of short straight
adjacent segments arranged tangentially on an imaginary smooth curved
leading edge with the segments successively intersecting each other so
that the overall effect is one of approximating a smooth retracted curved
leading edge by means of such short adjacent straight segments. Similarly,
the smooth retracted curved leading edge may be interrupted along its
length by one or more spaced-apart short segments of this type whereby
once again a smooth retracted curved leading edge is closely approximated.
Further, the swept back leading edge may be smooth or serrated.
In accordance with a particularly preferred embodiment of this invention at
least the innermost end of the leading edge of each planar blade is in
very close proximity to, and most preferably projects from, an arcuate
recess in the exterior of the hub, and most preferably such leading edge
extends substantially tangentially from the hub for a short distance
outwardly from the hub when the blade is in the neutral position--i.e.,
when the blade has been rotated on its axis such that the leading edge of
the blade falls in a plane perpendicular to the axis of the hub and
propeller shaft. The arcuate recess in the hub serves a twofold purpose.
First, it enables the inner end of the leading edge to be in direct or
substantially direct contact with the hub irrespective of the extent to
which the blade is rotated radially about its axis. This prevents or at
least greatly reduces the chances of vegetation or other debris becoming
wedged or entangled between the blade and hub. Secondly, the lateral ends
of the recess can serve as stops to prevent over-rotation of the blade in
either direction when adjustments in blade pitch are being made. Such
blades of course also possess the swept back curved leading edge described
above. For convenience such blades are sometimes referred to hereinafter
as the "grooved tangential swept back planar blades". In this connection,
the term "grooved" is used in the sense that the inner end portion of the
leading edge portion of the blade is positioned or is to be positioned
such that it fits into an arcuate groove in the exterior of the hub--it
does not mean that the blade itself is grooved. Experiments conducted
under actual service conditions have shown that grooved tangential swept
back flat planar blades of the type referred to in this paragraph can give
the very best results as they most effectively (a) cut through mud and
vegetation, (b) shed the cuttings, (c) avoid fouling at all locations on
the blade and hub, (d) drive the boat at high speeds when conditions
warrant, and (e) maneuver the boat under conditions where conventionally
propelled boats would become bogged down and hopelessly mired in the
swamp. Such blades are virtually foul-proof.
The blades of this invention can be utilized with any mechanism or system
which enables the stubs on the blades to be axially rotated such that the
pitch of the blades can be adjusted by the operator throughout the desired
range of positions, and yet held fast in the selected position. However it
is definitely preferred to utilize a variable pitch propeller drive and
adjusting mechanism of the type described hereinafter. Thus in accordance
with a further embodiment of this invention a variable pitch propeller
drive and adjusting mechanism is provided which comprises: (a) a hollow
drive shaft terminating in a hub; (b) a pitch adjusting shaft rotatable
with and longitudinally moveable in the drive shaft; (c) a pair of planar
blades (of the types described hereinabove) each with a cylindrical stub
on its inner end portion, the stubs extending into the hub through a pair
of hereinafter-referred-to bearings; (d) means within the hub translating
longitudinal movement of the pitch adjusting shaft into opposed rotational
movement of the stubs about an axis perpendicular to and extending through
the axis of the drive shaft; and (e) a pair of bearings mounted in and
affixed to the hub to accommodate such rotational movement of the
respective stubs; the apparatus being further characterized in that (f)
the blade stubs within the hub are shaped to axially abut and rotatably
engage each other; and (g) the pitch adjusting shaft is slidably fitted
within one or more bushings or bearings mounted in the drive shaft.
The longitudinal position of the pitch adjusting shaft within the hollow
drive shaft can be adjusted by means of a control or shift lever
mechanism. A feature of this invention is that the pitch of the planar
blades can thus be adjusted through a continuum of positions ranging from
fast forward to fast reverse without need for stops or other restraining
means imposed on the shift lever. Undesired changes in the pitch of the
planar blades due to torsional forces generated in the water by the
rotation therein of the blades around the axis of the drive shaft can be
successfully nullified without need for such stops or like restraining
means. Without desiring to be bound by theoretical considerations, it is
believed that at least two combined effects are responsible for such
nullification. First, undesired changes in the pitch of the rotating
planar blades is believed to be resisted by the axial abutment and
rotatable engagement between the ends of the stubs within the hub. This
mechanical arrangement is believed to couple and pit the torsion derived
forces from the blades against each other so that these forces tend to
neutralize each other. Secondly, it is believed that the friction of the
slidable fit of the pitch adjusting shaft within the bearing(s) or
bushing(s) in the drive shaft and the centrifugal forces generated by the
drive shaft bearing(s) and the pitch adjusting shaft rotating in unison
tend to resist undesired change in the longitudinal position of the pitch
adjusting shaft in the drive shaft, and as a consequence these factors
also tend to prevent undesired changes in the pitch of the planar blades
as the blades rotate in the water around the axis of the drive shaft.
Whatever the mechanism may be, the plain fact is that prototype systems of
this invention have been constructed in the manner disclosed and depicted
herein and found to work well in actual service for suitably long periods
of time.
Another feature of this invention is that by eliminating the need for stops
or other restraining means on the control or shift lever mechanism to
prevent unwanted pitch changes in the planar blades, the planar blades can
under special or emergency conditions be rotated around the axes of their
stubs. For example, if the planar blades strike a submerged log or other
substantial underwater obstacle, the extra torsional force imposed on them
by such impact can override the factors normally holding the blades in
their selected pitch positions and thus move the blades to another
position, usually neutral or close thereto, and thereby reduce the
likelihood of damage to the planar blades or to other parts of the
over-all mechanism.
It will be appreciated that while stops or other restraining means on the
control or shift lever mechanism are not required, they may be used, if
desired. In other words, it is not necessary to the practice of this
invention that the system be constructed so that such stops or other
restraining means are unnecessary. If such stops or other restraining
means are found necessary or desirable in any given type of construction,
they should of course be used. In one preferred system of this invention
when adapted for use with mud boats propelled with engines or other prime
movers providing up to about 25 horsepower (hp), the only such restraining
means used is a pair of stops to prevent the pitch of the planar blades to
exceed about 45 degrees from neutral in the forward or reverse position
and more preferably up to about 25 degrees in the reverse position, so as
to prevent the engine speed and load from becoming excessive and causing
possible damage to the engine. Within these extremes the pitch of the
planar blades may be adjusted as a continuum. This makes it possible to
maximize engine and boat performance which may vary from case to case
depending on the size and characteristics of the particular engine, boat
and planar blades used. As noted above, when grooved tangential swept back
planar blades are used, the lateral ends of the grooves can serve as the
stops in lieu of other forms of restraining means to prevent overrotation
of the blades. However, other forms of restraining means associated with
the control lever may be employed along with the grooves in order to keep
the blades in specific positions within the limits afforded by the lateral
ends of the grooves.
Thus, in a particularly preferred system of this invention adapted for use
with mud boats propelled with engines or other prime movers providing up
to about 25-35 horsepower, the restraining means used is comprised at
least in part of an arcuate groove or recess in the hub into which is
fitted the inner end of the leading edge portion of a planar blade, the
leading edge of which extends substantially tangentially from the hub for
a short distance outwardly from the hub when the blade is in the neutral
position, the lateral ends of the arcuate groove serving as stops to
prevent overrotation of the blades on their axes.
Another embodiment of this invention provides a variable pitch propeller
drive and adjusting mechanism which is readily serviced (e.g., packed with
grease or other suitable lubricant) and, if need be, repaired. This
mechanism comprises (a) a hollow drive shaft; (b) an open-ended hollow
housing mounted on the end of the shaft and rotatable therewith; (c) a hub
end cap detachably secured to the housing to cover the open end thereof
and thereby form a hollow hub; (d) a pitch adjusting shaft rotatable with
and longitudinally moveable in the drive shaft; (e) a pair of planar
blades (of the types described hereinabove) each with a cylindrical stub
on its inner end portion, the stubs extending into the hub through a pair
of bearings (referred to hereinafter); (f) means within the hub
translating longitudinal movement of the pitch adjusting shaft into
opposed rotational movement of the stubs about an axis perpendicular to
and extending through the axis of the drive shaft; and (g) a pair of
bearings in the hub to accommodate such rotational movement of the
respective stubs, each such bearing comprising a split bushing with
one-half of the bushing mounted in and affixed to a recess in the housing
at its open end and the other half of the bushing mounted in and affixed
to an opposed recess in the hub end cap. It will be seen that this
construction enables ready access to the means within the hub translating
longitudinal movement of the pitch adjusting shaft into opposed rotational
movement of the stubs, these being the elements that require most
servicing (lubrication).
In each of the foregoing embodiments other features of this invention may
be and preferably are employed. For example, the means translating
longitudinal movement of the pitch adjusting shaft into opposed rotational
movement of the stubs comprises (i) a yoke mounted on the end of the pitch
adjusting shaft, the yoke including a pair of ears extending
longitudinally beyond the end of the pitch adjusting shaft; (ii) a pair of
lobes, each integral with a respective stub and extending radially along
an axis perpendicular to the axis of the stub thereby forming a crank
thereon, said lobes extending in generally opposite directions from each
other; and (iii) a pair of links, each pivotally connected to a respective
ear of the yoke and to the crank of the proximate stub. In mechanisms
adapted for use in marshy areas containing marsh grasses or like
vegetation, it is preferred that the drive shaft be rotatably supported
within a casing, which casing has elongated substantially triangular fins
mounted on and extending radially outwardly from opposite sides of its
exterior such that the fins each provide in profile an inclined plane of
progressively increasing height terminating in front of and in proximity
to the transverse circular locus of rotation of the planar blades, the
apex of such inclined plane extending radially to at least about the
midpoint of the radial length of the blades. Another preferred feature for
inclusion in such apparatus are (i) means for mounting a prime mover above
the hollow drive shaft, and (ii) means for affixing an endless belt
between the prime mover and the hollow drive shaft to enable the drive
shaft to be rotated by the prime mover.
The above and still other embodiments and features of this invention should
be readily apparent from the ensuing description, appended claims and
accompanying drawings.
THE DRAWINGS
FIG. 1 is a side view of a preferred mechanism of this invention.
FIG. 2 is a top view, partly in phantom, of the mechanism of FIG. 1.
FIG. 3 is a section, partly in phantom, taken along line 3,3 of FIG. 1.
FIG. 4 is a side view of the hollow drive shaft with an open-ended hollow
housing affixed thereto.
FIG. 5 is a front view of the inside of a hub end cap detachably securable
to the hollow housing of FIG. 4.
FIG. 6 is an exploded side view in vertical section of the drive shaft and
the hollow housing of FIG. 4 together with the hub end cap of FIG. 5.
FIG. 7 is a side view of a pitch adjusting shaft longitudinally slidable in
bushings disposed in the drive shaft of FIGS. 4 and 6.
FIG. 8 is a top view of the pitch adjusting shaft of FIG. 7.
FIG. 9 is a back view of the outside of the hub end cap of FIG. 5.
FIG. 10 is a side view, partly in section, of a hub with means therein for
translating longitudinal movement of the pitch adjusting shaft into
rotational movement for adjusting the pitch of the blades.
FIG. 11 is a transverse exploded view of a pair of propeller blades each
with a cylindrical stub and a lobe utilized, inter alia, for translating
longitudinal movement of the pitch adjusting shaft into rotational
movement for adjusting the pitch of the blades.
FIG. 12 is an end view taken along line 12,12 of FIG. 11 and showing, inter
alia, a generally planar blade having convex outer transverse surface.
FIG. 13 is a transverse cross-section of a blade having a generally flat
outer surface and one relatively thick edge and one relatively thin edge,
the view taken along line 13,13 of FIG. 11.
FIG. 14 is an elevational view of the back end of a hub into which are
fitted a pair of flat planar blades of preferred configuration pursuant to
this invention.
FIG. 15 is a view of the upper blade of FIG. 14 looking in the direction of
line 15,15 of FIG. 14.
FIG. 16 is a section of the upper blade of FIG. 14 taken along line 16,16
of FIG. 14.
FIG. 17 is an elevational view of the back end of a hub into which are
fitted a pair of bent planar blades of preferred configuration pursuant to
this invention, these blades being adapted for rotation in the clockwise
direction (as viewed in this Figure).
FIG. 18 is a view of the upper blade of FIG. 17 looking in the direction of
line 18,18 of FIG. 17.
FIG. 19 is a section of the upper blade of FIG. 17 taken along line 19,19
of FIG. 17.
FIG. 20 is an elevational view of the back end of a hub into which are
fitted a pair of bent planar blades of preferred configuration pursuant to
this invention, these blades being adapted for rotation in the
counter-clockwise direction (as viewed in this Figure).
FIG. 21 is a view of the upper blade of FIG. 20 looking in the direction of
line 21,21 of FIG. 20.
FIG. 22 is a section of the upper blade of FIG. 20 taken along line 22,22
of FIG. 20.
FIG. 23 schematically depicts in plan view the positioning of the planar
blades in the fast forward position in a system involving clockwise
rotation (as viewed in the direction of the arrow therein).
FIG. 24 schematically depicts in plan view the positioning of the planar
blades in a reverse position in a system involving clockwise rotation (as
viewed in the direction of the arrow therein).
FIG. 25 is an elevational view of the back end of a hub into which are
fitted a pair of grooved tangential swept back flat planar blades of
particularly preferred configuration pursuant to this invention.
FIG. 26 is a view of the upper blade of FIG. 25 looking in the direction of
line 26,26 of FIG. 25.
FIG. 27 is a section of the upper blade of FIG. 25 taken along line 27,27
of FIG. 25.
FIG. 28 is a top plan view of the upper blade and the upper portion of the
hub of FIG. 25.
FIG. 29 is a fragmentary section of the hub of FIG. 25 taken along line
29,29 of FIG. 28.
FIG. 30 is an elevational view, partly in section, of a hub and a pair of
grooved tangential swept back flat planar blades with a preferred
mechanism within the hub for rotating the blades on the axis of their
respective stubs.
DESCRIPTION OF PREFERRED EMBODIMENTS
In order to still further illustrate the practice and advantages of this
invention reference is now made to the Drawings in which like numerals
represent like parts among the several views. The Drawings, which are not
to scale, depict and illustrate only certain preferred forms of the
invention. Other forms of the invention and apparatus provided thereby
will be readily apparent from a consideration of this entire disclosure.
The Planar Blades of the Invention
Turning first to FIGS. 14 through 16, the flat planar blades 46 of this
invention in the form therein depicted have a relatively sharp leading
edge 51 and a relatively thick or blunt trailing edge 47. Each blade is
affixed at its inner end as by welding or the like to a cylindrical stub
50 which is adapted to be axially rotated by adjusting means, preferably
of the type described hereinafter. Such rotation allows the pitch of the
blades to be adjusted. Hollow hub 45 contains some of the mechanism (not
shown in FIGS. 14-16, but a preferred form of which is described
hereinafter in connection with FIGS. 10, 11 and 30) for effecting such
axial rotation. In the system as depicted in FIGS. 14-16, hub 45, and each
blade 46 and its stub 50, are rotated in the direction of arrow 90 by a
drive shaft and drive train (not shown in FIGS. 14-16, but a preferred
form of which is described hereinafter in connection with FIGS. 3-11) so
that leading edge 51 cuts into the water. It is to be understood that if
the rotation by the drive shaft and drive train is arranged to be in the
counter-clockwise direction (opposite to the clockwise direction of arrow
90) then each of the flat planar blades 46 of FIG. 14 would be rotated
180.degree. on the axis of its stub 50 so that the positions of the
leading edge 51 and the trailing edge 47 would be the reverse of the
positions shown. The swept back configuration of leading edge 51 as
depicted in FIG. 14 should be noted. Of this, more will be said
hereinafter.
FIG. 15 illustrates the fact that in their most preferred form the
respective faces 92 and 93 of flat planar blades 46 are essentially
completely flat from inner end to outer end with only a small degree of
curvature or taper or thinning out as at 94a near the outer end. FIGS. 15
and 16 illustrate the fact that in their most preferred form the
respective faces 92 and 93 of flat planar blades 46 are likewise
essentially completely flat from leading edge 51 to trailing edge 47, but
that the thickness of the blade is more or less progressively increased
from thin edge 51 to thick edge 47. The forward edge portion of the blade
may additionally be sharpened or thinned out even more near the leading
edge 51 as at 94b. Trailing edge 47 may be squared off (as shown) or it
may be rounded off so that there are no relatively sharp corners. Likewise
it may be tapered down in thickness. In short, the thicker portion of the
blade is either at the trailing edge of the blade or is somewhere between
about the median portion of the blade and its trailing edge. The presence
of the thicker portion of the blade is to insure that the blade has
sufficient strength to apply the necessary force against the water to
propel the boat. For best results face 92 --the face away from the rear of
the boat--should be flat and any taper or the like should be in face 93
(such as is depicted in FIGS. 15 and 16). The blade may be thin and
completely uniform in cross section (e.g., 1/32 inch) if made from a
material having sufficient strength to propel the boat without becoming
distorted or undergoing physical deterioration (fatigue) after prolonged
usage.
FIGS. 17 through 19 depict in a preferred configuration bent planar blades
46a. It can readily be seen that these bent planar blades can possess all
of the structural features as the flat planar blades just described, but
differ therefrom in that they possess a progressive bend along their
outermost portions. This bend preferably commences at a locus 95 which is
between about 1/2 to about 3/4 (most preferably about 2/3) the distance
from the inner end and the outer end of the blade. The blades depicted in
these Figures are adapted for use in propulsion systems in which the
propeller shaft and hub 45 rotate clockwise (when viewed from a location
behind the boat and propeller) in the direction of arrow 97. Thus in this
case the relatively thin leading edge 51 of the upper blade in FIG. 17
(the blade in the 12 o'clock position) is on the right hand side of FIG.
17, since this is the direction toward which the blade is rotated by
rotation of the propeller shaft. When this same blade is rotated to the 6
o'clock position (the position of the lower blade in FIG. 17), its leading
edge will of course be toward the left hand side of that Figure. As FIG.
18 indicates, the bend of planar blades 46a,46a is toward the front of the
boat (i.e., toward the direction in which the boat normally travels). It
will be seen that both blades 46a,46a are of the same geometrical and
structural configuration--they are interchangeable with each other.
Therefore, for systems in which the rotation is clockwise, only one type
of blade-- a blade preferably configured as blade 46a in FIGS. 17-19--need
be manufactured and maintained in inventory, and moreover in the event one
blade is damaged it can be replaced without need for replacing the entire
propeller assembly as is often the case. Nevertheless, to insure optimum
performance it may be desired to substitute a matched pair of new
replacement blades in the event one of the blades in the system becomes
damaged.
Once again the swept back configuration of leading edge 51 as depicted in
this case in FIG. 17 should be noted. Of this, more will be said
hereinafter.
FIGS. 20 through 22 depict in a preferred configuration bent planar blades
46b. It can readily be seen that these bent planar blades possess all of
the structural features as the bent planar blades 46a just described, but
differ therefrom in that the positions of the leading edge 51 and the
trailing edge 47 are reversed relative to the progressive bend along their
outermost portions. As in the embodiment depicted in FIGS. 17-19, this
bend preferably commences at a locus 95 which is between about 1/2 to
about 3/4 (most preferably about 2/3) the distance from the inner end and
the outer end of the blade. However the blades depicted in FIGS. 20-22 are
adapted for use in propulsion systems in which the propeller shaft and hub
45 rotate counter-clockwise (when viewed from a location behind the boat
and propeller) in the direction of arrow 99. Thus in this case the
relatively thin leading edge 51 of the upper blade in FIG. 20 (the blade
in the 12 o'clock position) is on the left hand side of FIG. 20, since
this is the direction toward which the blade is rotated by rotation of the
propeller shaft. When this same blade is rotated to the 6 o'clock position
(the position of the lower blade in FIG. 20), its leading edge will of
course be toward the right hand side of that Figure. As FIG. 21 indicates,
the bend of planar blades 46b,46 b is toward the front of the boat (i.e.,
toward the direction in which the boat normally travels). It will be seen
that both blades 46b,46b are of the same geometrical and structural
configuration--they are interchangeable with each other. Therefore, for
systems in which the rotation is counter-clockwise, only one type of
blade--a blade preferably configured as blade 46b in FIGS. 20-22--need be
manufactured and maintained in inventory, and moreover in the event one
blade is damaged it can be replaced without need for relacing the entire
propeller assembly as is often the case. Here again, to insure optimum
performance it may be desired to substitute a matched pair of new
replacement blades in the event one of the blades in the system becomes
damaged.
FIGS. 14, 17, and 20 illustrate a very important feature of the planar
blades of this invention, namely that the leading edge 51 is swept back or
retracted for a substantial portion of its length (preferably more than
50% of the distance from inner end to outermost end). This permits the
blade to slice through the medium in which it being rotated and thus a
substantial portion of the leading edge does not confront the medium
head-on or tend to force the medium inwardly toward the hub, but rather a
substantial portion of the leading edge tends to force the medium
outwardly away from the hub. This may explain why such blades are able to
cut through wet mud and vegetation under conditions where a
helically-twisted or even a paddle-shaped or rectangularly shaped blade
could not operate. Whatever the mechanism or explanation, this feature has
been found in actual practice to greatly reduce the incidence of boats
becoming mired and bogged down when operating in wet mud or in thickly
overgrown marshy areas.
FIGS. 23 and 24 schematically illustrate how the pitch of the planar blades
46 (whether they are flat planar blades 46 or bent planar blades 46a or
46b) can be adjusted for forward and rearward travel, respectively. In
these Figures the drive shaft 14 (shown for simplicity as a line) and hub
45 are caused to rotate in a clockwise direction when viewed in the
direction of arrow 65 (i.e., viewed from a location behind the boat and
propeller, and looking toward the direction in which the boat normally
travels). The leading edge 51 of blade 46 (shown for simplicity as a line)
is thus toward the top of these Figures since these Figures are plan views
with the viewer of course looking down at the system depicted. In FIG. 23
planar blade 46 is in a fast forward position with angle beta being as
much as 45.degree.. In FIG. 24 planar blade 46 is in a reverse position
with angle gamma being as much as 45.degree., but preferably no more than
about 25.degree.. When blade 46 is axially rotated so that its plane
coincides with transverse plane 85 (i.e., angle beta in FIG. 23 and angle
gamma in FIG. 24 is 0.degree.), the blades are in their neutral position
and the boat is neither driven forward or in reverse. The preferred system
of this invention enables these changes in blade pitch to be made quickly,
easily and safely through a continuum of positions ranging from fast
forward (FIG. 23) to reverse (FIG. 24). Thus flat bottom boats even when
operated in thickly vegetated, muddy marshes can now be maneuvered so that
they do not become stuck or mired. Persons in south Louisiana having
first-hand familiarity with the problems that can be encountered in such
operation have expressed, often spontaneously, and occasionally in less
than polite language, their utter amazement at the handling
characteristics and maneuverability and performance of a flat bottom boat
equipped with a preferred system of this invention utilizing a pair of
flat planar blades 46 and a mere 18 hp gasoline engine as the power
source.
A most preferred planar blade construction pursuant to this invention is
illustrated in FIGS. 25 through 29 to which attention is now invited.
Depicted in these figures are the grooved tangential swept back flat
planar blades of this invention. It can be seen that in this configuration
the blades possess the swept back (retracted) leading edge feature and
otherwise resemble the blades of FIGS. 14-22 described above except that
the inner portion of leading edge 51 projects substantially tangentially
from hub 45 for part of the distance from inner end toward the outer end
(i.e., along segment "T") when the blades are in or close to their neutral
position (depicted in FIG. 28) where the blade is transverse or
substantially transverse to the axis of the drive shaft (not depicted in
FIGS. 25-29) and of hub 45. In addition, the inner end of the leading edge
portion fits into an arcuate groove 77 shaped to permit and accommodate
rotation of the blade in either direction from neutral (as depicted by
arrows 98 in FIG. 28). To facilitate an understanding of this grooved
construction, arcuate groove 77 is depicted in plan in FIG. 28 as if the
groove is in a flat planar surface rather than being cut into the surface
of a cylindrical surface of hub 45, which in fact it is. The distortion of
arcuate groove 77 when viewed in a plan view as it actually exists in the
cylindrical surface of hub 45 might tend to be somewhat confusing, hence
the simplification for the sake of better communicating the concepts
involved in the actual construction. In this same connection, it will be
appreciated that another such groove would be provided for each blade
carried by the hub, in this case one additional groove (not shown) for the
blade extending from the opposite side of hub 45.
The respective ends 79 of groove 77 serve as stops to prevent over-rotation
of the blade in either such direction. As can be appreciated (and as
indicated in FIG. 29) groove 77 becomes deeper when proceeding in the
direction of midpoint (i.e., transverse to the axis of hub 45) to the
respective ends 79,79. The planar blades of this invention which include
these tangential and grooved configurations possess all of the
advantageous features of the blades of FIGS. 14-22, but additionally have
the advantage that vegetation and other debris rarely if ever become
entangled with the blades or wedged between the blades and hub. As a
consequence, these particularly preferred blades enable operation in
swamps with an efficiency which, to the best of our knowledge and belief,
has never been achieved heretofore with any other propeller design, drive
system and engine of equal horsepower.
As will be appreciated by those skilled in the art, the amount of surface
area of the blades used should not require driving power in excess of the
power available from the engine or other prime mover being used to supply
the power needed to propel the boat under the service conditions to be
encountered. If, in other words, the blades are too large to be
effectively driven through the water or wet mud or vegetation-rich swamp
by a given engine, one should either use smaller blades of the same
configuration or a more powerful engine, or both, so that the prime mover
has the capacity to effectively propel the boat under the service
conditions to be encountered. On the other hand, the surface area of the
blades should be large enough to take advantage and make effective use of
the power available from the engine being used. The relationship between
blade surface area and engine horsepower to achieve best performance will
depend on various factors such as the size and shape of the boat hull, the
number of blades being used, the load to be carried in the boat, the
frictional characteristics of the drive train, the density of the wet mud
and foliage in which the boat may be operated, and so on. The following
relationships, which are presented for purposes of illustration and not
limitation, should be of help in designing or selecting components for a
two-bladed propeller and drive and pitch-adjusting system of the type
described herein:
______________________________________
Approximate Number of
Square Inches of Surface Area
Engine Horsepower
for One Face of One Planar Blade
______________________________________
12-14 About 6 to about 7
18 About 8 to about 9
25 About 10 to about 11
______________________________________
It will be seen that, generally speaking, the higher the horsepower, the
larger the blade surface area. Thus with a 50 hp engine the most suitable
blade surface area will be larger than about 11 square inches, and with
100 hp engines it will be larger still.
Referring again to FIGS. 25 to 29, another surprising feature of these
particular blades is that when the surface area is adjusted as indicated
in the above table and this surface area is properly apportioned between
the areas fore and aft of centerline CL in FIG. 25 the best overall
performance can be achieved. For example, with an 18 hp engine, a variable
pitch control and drive system of the type described hereinafter, and with
a pair of variable pitch grooved tangential swept back flat planar blades
of the type depicted in FIG. 25 in which the ratio between area "A" to the
foreward side of centerline CL and area "B" to the rearward side of
centerline CL is about 45:55, there is no tendency for control lever 11 of
the system described hereinafter (see FIGS. 1 and 2) to move in either
direction even when not held in any given position by the operator.
However the maximum boat speed is not obtainable from this particular
system under these particular circumstances. When the same type of blade
is slightly modified such that the ratio between area "A" to the foreward
side of centerline CL and area "B" to the rearward side of centerline CL
is about 42:58 again there is no tendency for control lever 11 to move in
either direction even when not held in any given position by the operator,
and in this particular case the boat can be operated smoothly at all
speeds, including high speeds. When under these same conditions this same
ratio is adjusted to about 40:60 very similar results are achieved except
that there is a slight tendency for control lever 11 to move when not held
in position by the operator, but only at the highest speeds of boat
operation. And when under these same conditions this same ratio is
adjusted to about 38:62, very high speed boat operation can be achieved
but in this particular case and under these particular conditions there is
a sufficient tendency for control lever 11 to move when not held in
position by the operator that it is desirable to provide means for holding
lever 11 in whatever position it is moved into by the operator. Each of
the foregoing situations provides acceptable operation pursuant to this
invention. Thus the selection of any given ratio as between area "A" and
area "B" will depend on the type of operation and service sought to be
designed into any given system. If speed is of paramount importance, a
ratio such as 38:62 may be selected and means provided to lock lever 11 in
whatever position the operator may select. On the other hand, if a system
in which lever 11 is unrestrained and automatically stays where placed by
the operator, but high speed operation is not an objective, a ratio of
about 45:55 may be selected. An ideal compromise in order to achieve both
high speed and unrestrained operation of lever 11 would involve use of a
ratio of about 42:58. The foregoing relationships among engine horsepower,
blade configuration, blade size and blade area distribution, which are
presented for purposes of illustration and not limitation, should be of
further help in designing or selecting components for a two-bladed
propeller and drive and pitch-adjusting system of the type described
herein.
Variable Pitch Adjusting System and Drive Mechanism
At the outset it is to be understood and appreciated that the blades of
this invention can be effectively used with any suitable drive and
pitch-adjusting system, such as those described in some of the patents
cited hereinabove. However for best results a system of the type described
hereinafter should be used, and the combination of the blades of this
invention and a system of the type described hereinafter constitutes an
especially preferred embodiment of this invention.
The preferred form of variable pitch and adjusting mechanism and drive
system for use with the planar blades of this invention, in its preferred
form depicted, is especially adapted for use with flat bottom mud boats
utilizing a relatively small engine (e.g., up to about 25 hp) as the prime
mover 10 (note FIG. 3). Platform 12 is disposed above the inner end
portion of hollow drive shaft 14, and serves as a means for mounting prime
mover 10 on the upper portion of the mechanism to conserve space within
the boat (not shown). As best seen in FIG. 3, an endless belt 16 driven by
pulley 18 passes over and rotates drive shaft 14. A pulley (not shown) may
be affixed to drive shaft 14 to accommodate belt 16, if desired. Rotatable
belt tensioner 20 is adjustably secured in position to enable the tension
on belt 16 to be properly adjusted. Thus operation of prime mover 10
causes rotation of drive shaft 14 by means of belt 16.
Drive shaft 14 is rotatably secured along a portion of its length within
shaft housing 22 by means of bearings (not shown). Drive shaft 14 is
hollow along its length (note FIG. 6) and in the form depicted is affixed
at its outer end to open-ended hollow housing 24 which is rotatable
therewith. Mounted within drive shaft 14 is pitch adjusting rod or shaft
26 which is longitudinally slidable within bearings or bushings 28 secured
within drive shaft 14. Shaft 26 and bearings or bushings 28 rotate in
unison with drive shaft 14 and housing 24. Hub end cap 30 is adapted to be
detachably secured to housing 24 by means of threaded studs 32 (which pass
through matching apertures 34) and exteriorly affixed nuts 36. A pair of
split bushings 38 are mounted and affixed (for example by welding) in
matching recesses 40 on opposite sides of the outer end of housing 24, and
a matching pair of split bushings 42 are mounted and similarly affixed in
matching recesses 44 on opposite sides of the inner end of end cap 30.
Thus when end cap 30 is secured to housing 24 there is formed a hollow hub
45 together with a pair of bearings formed from the respective opposed
pairs of stationary split bushings 38,42. As seen from FIGS. 1 and 2,
planar blades 46 are carried by hub 45.
Within hub 45 is contained means for translating longitudinal movement of
shaft 26 into rotational movement of blades 46 around their own axes in
order to change the pitch of the blades. Secured to the outer end portion
of shaft 26 is yoke 48 comprising a pair of laterally spaced, axially
projecting ear portions 49. Secured to the interior portion of each blade
46 is a cylindrical stub 50 having a lobe portion 52 integral therewith.
As can be seen from FIGS. 10, 11 and 12, the lobe portions 52 extend
radially along an axis perpendicular to the axis of stub 50 and thereby
form a crank thereon. As shown by FIG. 11, the two lobe portions 52 extend
in generally opposite directions, one extending generally upwardly and the
other generally downwardly. A link 55 is pivotally mounted on and connects
each of the repective lobe portions 52 to the transversely proximate ear
portion 49 of yoke 48. Thus as viewed in FIG. 10 one of the links 55 is
connected between the transversely remote ear portion 49 and the
transversely remote lobe portion 52. It will be understood and appreciated
therefore that the same linkage applies to the transversely proximate ear
portion 49 and the transversely proximate lobe portion 52 (not shown in
the sectional view of FIG. 10) nearer the viewer, except that the
positions of this proximate link 55 and this proximate lobe portion 52
will be inverted as compared to those depicted in FIG. 10. Thus as
indicated for example in FIGS. 10 and 12, longitudinal movement of shaft
26 causes rotation of the respective lobe portions 52 in opposite
directions which in turn causes the respective stubs 50 and planar blades
46 to rotate around their axes in opposite directions so that the pitch of
the planar blades can thereby be adjusted within a continuum of positions.
FIG. 30 depicts a hub 45 containing means as described above for
translating longitudinal movement of shaft 26 into rotational movement of
blades 46 around the axis of their respective stubs 50 in order to change
the pitch of the blades. In FIG. 30 the blades are a pair of grooved
tangential swept back planar blades of the type described hereinabove. The
blades are attached to their respective stubs 51 by means of a ground weld
as at 75.
A feature of this invention is illustrated in FIGS. 11 and 30, viz., the
particularly preferred way in which the blade stubs 50 axially abut and
rotatably engage each other. As depicted in FIGS. 11 and 30, the inner end
of each stub 50 has an axially positioned cylindrical recess 58 thereby
forming an annular face 59 on the end of each stub. The recesses are sized
and shaped to slidably receive dowel 57 to keep both stubs in axial
alignment. In addition, the opposed faces 59,59 abut each other around
dowel 57. This construction provides a large area of slidable contact
between the respective stubs and as explained hereinabove, it is believed
that this coupling of opposed torsion derived forces imposed on the blades
46 as they are rotated in the water around the axis of shaft 14 tends to
pit these counter-rotational forces against each other so that the
selected pitch of the blades resists change caused by such forces except
in extenuating circumstances such as a blade striking a heavy submerged
object. In this same connection, FIG. 10 illustrates that while a
longitudinal force imposed on shaft 26 will cause rotation of stub 50 and
a change in the pitch of propeller blade 46, undesired longitudinal
movement of shaft 26 tends to be resisted by the frictional contact
between shaft 26 and bushing 28. Further, since the entire unit depicted
in FIG. 10 is rotating around the axis of shaft 26, it is believed that
centrifugal forces generated in such rotation tend to provide resistance
against undersired longitudinal movement of shaft 26. It is to be
understood and appreciated, however, that this invention is not intended
to be limited, nor should it be limited, to any theory of operation. The
invention has been found to work, and to work very well under actual
service conditions, irrespective of the theoretical niceties of why it
works.
Another important advantage of the construction depicted in FIG. 11 is the
fact that both blade-stub assemblies are identical to each other, both in
size and shape and weight. Thus if one planar blade is damaged during use,
it can be replaced by another identical blade-stub assembly--there is no
need to stock two differently constructed blade-stub assemblies. Moreover
the fact that the two halves of the blade-stub assemblies are the same
(except disposed in inverted positions relative to each other, as
depicted) insures that the entire system is well balanced and will provide
smooth operation. In this connection, it is desirable in the case of
stainless steel blades to match the weight of the respective blade-stub
assemblies to within about 1/2 of an ounce.
FIGS. 12 and 13 illustrate respective features of the planar blades. In one
form the blades preferably have in transverse profile a convex shape as
indicated in FIG. 12 whereas in other preferred forms they have a
substantially flat transverse profile as indicated in FIG. 13. FIG. 13
illustrates still another preferred feature, namely that the blades,
whether of a convex or flat generally planar profile, can have one
relatively thick edge 47 and in any event do have one relatively thin edge
51, the latter serving as the leading edge. This feature has been found
particularly desirable in mechanisms used in propelling mud boats in
swampy or marshy areas. For example, with a pair of blades each having on
one side a facial area of about ten square inches, one edge (the trailing
edge) preferably has a thickness in the range of about 1/8 to about 3/8
inch, most preferably about 1/4 inch, whereas the other edge (the leading
edge) should be sharp or relatively sharp, e.g., it is preferably no more
than about 1/32 inch in thickness.
As depicted in FIGS. 1 and 2 control lever 11 is pivotally connected to the
mechanism so that forward or rearward movement of the lever as indicated
by the arrows in FIG. 1 causes longitudinal movement of shaft 26 and
consequent adjustment in the pitch of the blades. As noted hereinabove,
lever 11 need not be equipped with stops for specified intermediate
positions, although such stops may be provided, if desired. It is however
desirable to provide stops to confine the limits of forward and reverse
travel of lever 11 so that the engine or other prime mover is not
subjected to excessive speeds or stress during operation. In the system of
FIGS. 25-30 the ends 79,79 of groove 77 can serve as stops.
FIG. 1 also illustrates the fact that for flat bottom boat operation the
mechanism is preferably mounted on the boat so that its angle of rearward
decline (angle alpha) from the horizontal is between about 10 and about 12
degrees, most preferably about 10 degrees.
Other preferred features depicted in FIGS. 1 and 2 include the provision of
an elongated mounting plate 15 above a substantial portion of shaft
housing 22. Plate 15 is placed against the bottom of a flat bottom boat so
that the propeller is below but close to the rear transom of the boat, and
the overall mechanism of this invention is then bolted to the boat through
apertures in plate 15 and the bottom of the boat. It will thus be
appreciated that shaft housing 22 extends up into the boat through a
suitable opening in the boat which is covered by plate 15. Keel or rod 17
which may be square, round, or etc. and either solid or hollow, is
preferably about 5/8 to 3/4 inch in cross-section. It declines rearwardly
somewhat more than angle alpha and thus as the boat is propelled
forwardly, rod 17 tends to impose an upward lift in the event a submerged
stump or other obstacle is encountered. Upper vertical plate 19 provides
connection between the median lower portion of mounting plate 15 and the
median upper portion of shaft housing 22. Lower vertical plate 21 provides
connection between the lower median portion of shaft housing 22 and the
median upper portion of rod 17.
As can be seen from FIGS. 1 and 2, affixed to the rearward portion of shaft
housing 22 are a pair of elongated triangular fins 23,23 which extend
radially outwardly from opposite sides of the exterior of housing 22. As
depicted in FIG. 2, each such fin provides in profile (i.e., when viewed
from above) an inclined plane of progressively increasing height
terminating in front of and in proximity to the transverse circular locus
of rotation of blades 46,46. The apex of this triangular profile extends
(as depicted) to at least about the midpoint of the radial length of the
blades to the extent they project from hub 45. These fins assist in
preventing fouling when operating in marshy areas thick with grasses and
other plant life.
The boat itself may be made of metal such as aluminum, plastics, laminates,
wood or the like.
Boats equipped with systems of this invention are generally operated at
conventional engine speeds, e.g., about 2500 to about 3200 rpm, and at
slower idle speeds. Among the advantages of this invention is the fact
that the system may be shifted very easily, smoothly, and rapidly from
full speed forward to full speed reverse without changing engine
speed--none of this is possible with conventionally equipped power boats.
This invention thus makes possible the following advantages:
1) Fouling of propeller blades can be avoided even when operating in
thickly vegetated marshy areas.
2) Boats can be maneuvered such that they can extricate themselves from mud
and vegetated areas in which conventional boats would become mired and
bogged down.
3) Boats can be operated at a wide range of speeds, both in forward and in
reverse.
4) Boats can be stopped easily, rapidly and smoothly, and can be caused to
reverse directions, all without changing engine speed.
5) Systems can be provided in which conventional restraining means for the
pitch control lever need not be used.
6) Durable systems easy to service and maintain can be provided.
7) Very quiet boat operation is readily achieved.
8) Ordinary low to medium horsepower engines can be used.
9) Systems can be provided which do not occupy much boat space.
This invention is susceptible to considerable variation in its practice and
it is not intended that it be limited by the illustrative embodiments
described herein. Rather, this invention is embodied in the spirit and
scope of the ensuing claims.
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